INTENSIVE REARING OF POSTLARVAL MALAYSIAN PRAWNS (Macrobrachium rosenbergii) IN A CLOSED CYCLE NURSERY SYSTEM1

An intensive nursery concept incorporating artificial habitats, aquatic plants and recirculation of the rearing water was tested with juvenile Malaysian prawns (Macrobrachium rosenbergii). Two replicate systems were set up; each consisted of three interconnected tanks, one of which served as the biological filter for all three. A total of 24,150 juvenile prawns (mean weight 0.31 g) was used to examine three treatments: (I) stocking density of 1,617 prawns m-2 (150 ft-2) of tank floor; (2) density of 1,078 prawns m-2 (100 ft-2); and (3) density of 1,078 prawns m-2 (100 ft-2) with gravel biological filter in tank. Each treatment appeared once in each tank series. No differences in mean size or survival were detected among the treatments during the eight-week study. Survival averaged 81.5% on day 30 and 62.0% on day 56. Overall mean standing crops of 1,022 prawns 0.61 g in mean weight and 771 prawns 1.11 g in mean weight m-2 of tank floor were recorded on days 30 and 56, respectively. These data suggest that a nursery system of 200 m2 tank area could possibly produce sufficient 0.5-1 g juveniles to stock approximately 1.5-2 ha of ponds at a density of 10 prawns m-2. Coupling such nursery systems with grow-out ponds in temperate areas like South Carolina might markedly increase total production and mean prawn size. thereby increasing the value of the prawn crop.